Alright, finally doing some work to the 400 in my 79. Installing Summit headers, Edelbrock intake and 4v Holley carb. It also has some generic RV cam in it that was installed with the shop rebuild.
The EGR is coming off when the intake is installed, so I purchased the adjustable vacuum advance kit. I've got it all apart, but am not sure which spring(s) to install.

Here's what the instructions say:
There is also a list of spring combos that lists with all that the start advance RPM is 800, and between the 3 springs, full advance is at either 3800, 3500, or 3100 RPM.

I know these kits involve a lot of trial and error to eliminate ping, but I don't even know where to begin with which springs to install. On a mild motor like this, just pulling the EGR, where do I even begin?

 

I have been playing with the same kit for my 429. Read this article. It helped me understand more. fordmuscle.com/archives/2000/03/timing. Hope I got that right.

 

Thanks a ton for the link. I have a few 'adult beverages' in my system at the moment, so I'm not messing with it at the moment, but that's already been a good read, and a lot of help.

 

Had a few myself, Here is another site I found useful. reincarnation-automotive.com/Duraspark_distributor_recurve_instructions_index.h tml Hope that helps also.

 

So... With the EGR plate removed, should I be aiming towards full vacuum hitting at a higher or lower RPM range?
I'm not sure why I'm having a hard time absorbing all this info...

 

You have stepped yourself into one of the harder tunings of an engine so dont feel lost or dumb. Patience is the key and pay attention cause if you get this right you'll be able to help others in the future. I'am still trying to get mine just right not knowing the internal variables and Ive been beating at it for a long time. Since your close to sealevel, warmer climates, and a bigger cam start with the mid range timing settings in the kit and work from there. You may be able to advance it more and faster will be my guess. Please read the link as it may simplify it for you. http://www.malloryperformance.com/pdf/SetADvance.pdf

 

I put one of those on my 77 F150 it has a 351M (according to the decal)
I use this truck as a work truck. I didn't replace the springs at all.
I hooked the advance unit to ported vacum so that at a low RPM and high load (like 2500 lbs of gravel)situation the advance would be smaller than with a lighter load.

 

I'm thinking I'll replace the one spring with the mid-range spring, and start messing with it from there. The truck was having slight ping up hills when I'd hit the throttle when itwas all stock, except for the cam. I'd gone over the timing stuff a ton of times, but wasn't able to get it to have decent get up and go without pinging. I'll keep posting with progress (truck currently has no cab, and just got the transmission, t-case and headers on today. Doing the intake tomorrow, and either installing the Edelbrock carb my roommate has laying around, or rebuilding the Holley on his truck for mine. SHould be ready to run in the next week.

 

I was going to start a new thread about the problems, but I figured I'd update this one with the new questions:

Rebuilt Holley 650:
Got my motor all together. Drove it a bit yesterday, ran fine but was idling pretty high. The idle screw is backed pretty much all the way out. I understand a 650 will idle higher than the 2bbl 2150, but where is a normal idle for a 400/auto?
The problem I'm having is if I hit the throttle hard, it backfires through the carb. I've already installed a new power valve, and one of those 'power valve savers'

The exhaust was blowing black smoke (not as bad as when the power valve was blown though). The electric choke wasn't working, so I held it in the full open position and the smoke went away. Obviously way too rich. When I turn the mixture screws in all the way, it continues to run for a minute, then dies out. I've adjusted the floats properly, and I've got it now where it won't blow smoke, isn't dieseling, but still backfires when I hit the throttle hard.

Seeing as I'm pulling my hair out messing with the carb, I want to try and mess with the dizzy some more. I've replaced the large spring for a medium one, and haven't touched the vacuum canister yet. It backfires whether the (ported) vacuum line is hooked up or not. And I've messed with it between 0 and 8 degrees advance. Wondering if I should try different springs or what? I've been reading about all of this like crazy for a while now, but my brain just isn't wrapping around it fully. I think if I'm pointed in the right direction, it might get the wheels turning.

 

Aha! So I advanced the dizzy WAY far ahead and no backfire... Lighter springs it is!